Creates new module providing terminal session management using @xterm/headless:
- createTerminal(): spawn headless terminal emulator instances
- serializeAsHTML(): export terminal state as HTML
- disposeTerminal(): clean up resources
This replaces stateless ANSI processing with proper VT emulation that tracks
cursor position, screen buffer, and terminal attributes across output chunks.
Moved index.ts to src/server.ts and created stub files for types, db, auth,
and cli modules. Added minimal placeholder for dashboard. Removed generated
README.md in favor of CLAUDE.md and docs/plan.md.